; Bitmap pixel graphics routines for the CommanderX16 ; Custom routines to use the full-screen 640x480 and 320x240 screen modes. ; (These modes are not supported by the documented GRAPH_xxxx kernal routines) ; ; No text layer is currently shown, text can be drawn as part of the bitmap itself. ; Note: for similar graphics routines that also work on the C-64, use the "graphics" module instead. ; Note: for color palette manipulation, use the "palette" module or write Vera registers yourself. ; Note: this library implements code for various resolutions and color depths. This takes up memory. ; If you're memory constrained you should probably not use this built-in library, ; but make a copy in your project only containing the code for the required resolution. ; ; ; SCREEN MODE LIST: ; mode 0 = reset back to default text mode ; mode 1 = bitmap 320 x 240 monochrome ; mode 2 = bitmap 320 x 240 x 4c (TODO not yet implemented) ; mode 3 = bitmap 320 x 240 x 16c (TODO not yet implemented) ; mode 4 = bitmap 320 x 240 x 256c (like SCREEN $80 but using this api instead of kernal) ; mode 5 = bitmap 640 x 480 monochrome ; mode 6 = bitmap 640 x 480 x 4c ; higher color dephts in highres are not supported due to lack of VRAM gfx2 { ; read-only control variables: ubyte active_mode = 0 uword width = 0 uword height = 0 ubyte bpp = 0 bool monochrome_dont_stipple_flag = false ; set to false to enable stippling mode in monochrome displaymodes sub screen_mode(ubyte mode) { when mode { 1 -> { ; lores monochrome cx16.VERA_DC_VIDEO = (cx16.VERA_DC_VIDEO & %11001111) | %00100000 ; enable only layer 1 cx16.VERA_DC_HSCALE = 64 cx16.VERA_DC_VSCALE = 64 cx16.VERA_L1_CONFIG = %00000100 cx16.VERA_L1_MAPBASE = 0 cx16.VERA_L1_TILEBASE = 0 width = 320 height = 240 bpp = 1 } ; TODO modes 2, 3 not yet implemented 4 -> { ; lores 256c cx16.VERA_DC_VIDEO = (cx16.VERA_DC_VIDEO & %11001111) | %00100000 ; enable only layer 1 cx16.VERA_DC_HSCALE = 64 cx16.VERA_DC_VSCALE = 64 cx16.VERA_L1_CONFIG = %00000111 cx16.VERA_L1_MAPBASE = 0 cx16.VERA_L1_TILEBASE = 0 width = 320 height = 240 bpp = 8 } 5 -> { ; highres monochrome cx16.VERA_DC_VIDEO = (cx16.VERA_DC_VIDEO & %11001111) | %00100000 ; enable only layer 1 cx16.VERA_DC_HSCALE = 128 cx16.VERA_DC_VSCALE = 128 cx16.VERA_L1_CONFIG = %00000100 cx16.VERA_L1_MAPBASE = 0 cx16.VERA_L1_TILEBASE = %00000001 width = 640 height = 480 bpp = 1 } 6 -> { ; highres 4c cx16.VERA_DC_VIDEO = (cx16.VERA_DC_VIDEO & %11001111) | %00100000 ; enable only layer 1 cx16.VERA_DC_HSCALE = 128 cx16.VERA_DC_VSCALE = 128 cx16.VERA_L1_CONFIG = %00000101 cx16.VERA_L1_MAPBASE = 0 cx16.VERA_L1_TILEBASE = %00000001 width = 640 height = 480 bpp = 2 } else -> { ; back to default text mode cx16.r15L = cx16.VERA_DC_VIDEO & %00000111 ; retain chroma + output mode c64.CINT() cx16.VERA_DC_VIDEO = (cx16.VERA_DC_VIDEO & %11111000) | cx16.r15L width = 0 height = 0 bpp = 0 mode = 0 } } active_mode = mode if bpp clear_screen() } sub clear_screen() { monochrome_stipple(false) position(0, 0) when active_mode { 1 -> { ; lores monochrome repeat 240/2/8 cs_innerloop640() } ; TODO mode 2, 3 4 -> { ; lores 256c repeat 240/2 cs_innerloop640() } 5 -> { ; highres monochrome repeat 480/8 cs_innerloop640() } 6 -> { ; highres 4c repeat 480/4 cs_innerloop640() } ; modes 7 and 8 not supported due to lack of VRAM } position(0, 0) } sub monochrome_stipple(bool enable) { monochrome_dont_stipple_flag = not enable } sub rect(uword x, uword y, uword rwidth, uword rheight, ubyte color) { if rwidth==0 or rheight==0 return horizontal_line(x, y, rwidth, color) if rheight==1 return horizontal_line(x, y+rheight-1, rwidth, color) vertical_line(x, y+1, rheight-2, color) if rwidth==1 return vertical_line(x+rwidth-1, y+1, rheight-2, color) } sub fillrect(uword x, uword y, uword rwidth, uword rheight, ubyte color) { if rwidth==0 return repeat rheight { horizontal_line(x, y, rwidth, color) y++ } } sub horizontal_line(uword x, uword y, uword length, ubyte color) { if length==0 return when active_mode { 1, 5 -> { ; monochrome modes, either resolution ubyte separate_pixels = (8-lsb(x)) & 7 if separate_pixels as uword > length separate_pixels = lsb(length) repeat separate_pixels { ; TODO optimize this by writing a masked byte in 1 go plot(x, y, color) x++ } length -= separate_pixels if length { position(x, y) separate_pixels = lsb(length) & 7 x += length & $fff8 %asm {{ lsr length+1 ror length lsr length+1 ror length lsr length+1 ror length lda color bne + ldy #0 ; black bra _loop + lda monochrome_dont_stipple_flag beq _stipple ldy #255 ; don't stipple bra _loop _stipple lda y and #1 ; determine stipple pattern to use bne + ldy #%01010101 bra _loop + ldy #%10101010 _loop lda length ora length+1 beq _done sty cx16.VERA_DATA0 lda length bne + dec length+1 + dec length bra _loop _done }} repeat separate_pixels { ; TODO optimize this by writing a masked byte in 1 go plot(x, y, color) x++ } } cx16.VERA_ADDR_H &= %00000111 ; vera auto-increment off again } 4 -> { ; lores 256c position(x, y) %asm {{ lda color phx ldx length+1 beq + ldy #0 - sta cx16.VERA_DATA0 iny bne - dex bne - + ldy length ; remaining beq + - sta cx16.VERA_DATA0 dey bne - + plx }} } 6 -> { ; highres 4c ; TODO also mostly usable for lores 4c? color &= 3 ubyte[4] colorbits ubyte ii for ii in 3 downto 0 { colorbits[ii] = color color <<= 2 } void addr_mul_24_for_highres_4c(y, x) ; 24 bits result is in r0 and r1L (highest byte) %asm {{ lda cx16.VERA_ADDR_H and #%00000111 ; no auto advance sta cx16.VERA_ADDR_H stz cx16.VERA_CTRL ; setup vera addr 0 lda cx16.r1 and #1 sta cx16.VERA_ADDR_H lda cx16.r0 sta cx16.VERA_ADDR_L lda cx16.r0+1 sta cx16.VERA_ADDR_M phx ldx x }} repeat length { %asm {{ txa and #3 tay lda cx16.VERA_DATA0 and gfx2.plot.mask4c,y ora colorbits,y sta cx16.VERA_DATA0 cpy #%00000011 ; next vera byte? bne ++ inc cx16.VERA_ADDR_L bne ++ inc cx16.VERA_ADDR_M + bne + inc cx16.VERA_ADDR_H + inx ; next pixel }} } %asm {{ plx }} } } } sub vertical_line(uword x, uword y, uword lheight, ubyte color) { when active_mode { 1, 5 -> { ; monochrome, lo-res cx16.r15L = gfx2.plot.bits[x as ubyte & 7] ; bitmask if color { if monochrome_dont_stipple_flag { ; draw continuous line. position2(x,y,true) if active_mode==1 set_both_strides(11) ; 40 increment = 1 line in 320 px monochrome else set_both_strides(12) ; 80 increment = 1 line in 640 px monochrome repeat lheight { %asm {{ lda cx16.VERA_DATA0 ora cx16.r15L sta cx16.VERA_DATA1 }} } } else { ; draw stippled line. if x&1 { y++ lheight-- } position2(x,y,true) if active_mode==1 set_both_strides(12) ; 80 increment = 2 line in 320 px monochrome else set_both_strides(13) ; 160 increment = 2 line in 640 px monochrome repeat lheight/2 { %asm {{ lda cx16.VERA_DATA0 ora cx16.r15L sta cx16.VERA_DATA1 }} } } } else { position2(x,y,true) cx16.r15 = ~cx16.r15 ; erase pixels if active_mode==1 set_both_strides(11) ; 40 increment = 1 line in 320 px monochrome else set_both_strides(12) ; 80 increment = 1 line in 640 px monochrome repeat lheight { %asm {{ lda cx16.VERA_DATA0 and cx16.r15L sta cx16.VERA_DATA1 }} } } } 4 -> { ; lores 256c ; set vera auto-increment to 320 pixel increment (=next line) position(x,y) cx16.VERA_ADDR_H = cx16.VERA_ADDR_H & %00000111 | (14<<4) %asm {{ ldy lheight beq + lda color - sta cx16.VERA_DATA0 dey bne - + }} } 6 -> { ; highres 4c ; use TWO vera adress pointers simultaneously one for reading, one for writing, so auto-increment is possible if lheight==0 return position2(x,y,true) set_both_strides(13) ; 160 increment = 1 line in 640 px 4c mode color &= 3 color <<= gfx2.plot.shift4c[lsb(x) & 3] ; TODO with lookup table ubyte @shared mask = gfx2.plot.mask4c[lsb(x) & 3] repeat lheight { %asm {{ lda cx16.VERA_DATA0 and mask ora color sta cx16.VERA_DATA1 }} } } } sub set_both_strides(ubyte stride) { stride <<= 4 cx16.VERA_CTRL = 0 cx16.VERA_ADDR_H = cx16.VERA_ADDR_H & %00000111 | stride cx16.VERA_CTRL = 1 cx16.VERA_ADDR_H = cx16.VERA_ADDR_H & %00000111 | stride } } sub line(uword @zp x1, uword @zp y1, uword @zp x2, uword @zp y2, ubyte color) { ; Bresenham algorithm. ; This code special-cases various quadrant loops to allow simple ++ and -- operations. if y1>y2 { ; make sure dy is always positive to have only 4 instead of 8 special cases cx16.r0 = x1 x1 = x2 x2 = cx16.r0 cx16.r0 = y1 y1 = y2 y2 = cx16.r0 } word @zp dx = (x2 as word)-x1 word @zp dy = (y2 as word)-y1 if dx==0 { vertical_line(x1, y1, abs(dy) as uword +1, color) return } if dy==0 { if x1>x2 x1=x2 horizontal_line(x1, y1, abs(dx) as uword +1, color) return } word @zp d = 0 cx16.r13 = true ; 'positive_ix' if dx < 0 { dx = -dx cx16.r13 = false } word @zp dx2 = dx*2 word @zp dy2 = dy*2 cx16.r14 = x1 ; internal plot X if dx >= dy { if cx16.r13 { repeat { plot(cx16.r14, y1, color) if cx16.r14==x2 return cx16.r14++ d += dy2 if d > dx { y1++ d -= dx2 } } } else { repeat { plot(cx16.r14, y1, color) if cx16.r14==x2 return cx16.r14-- d += dy2 if d > dx { y1++ d -= dx2 } } } } else { if cx16.r13 { repeat { plot(cx16.r14, y1, color) if y1 == y2 return y1++ d += dx2 if d > dy { cx16.r14++ d -= dy2 } } } else { repeat { plot(cx16.r14, y1, color) if y1 == y2 return y1++ d += dx2 if d > dy { cx16.r14-- d -= dy2 } } } } } sub circle(uword @zp xcenter, uword @zp ycenter, ubyte radius, ubyte color) { ; Midpoint algorithm. if radius==0 return ubyte @zp xx = radius ubyte @zp yy = 0 word @zp decisionOver2 = (1 as word)-xx ; R14 = internal plot X ; R15 = internal plot Y while xx>=yy { cx16.r14 = xcenter + xx cx16.r15 = ycenter + yy plot(cx16.r14, cx16.r15, color) cx16.r14 = xcenter - xx plot(cx16.r14, cx16.r15, color) cx16.r14 = xcenter + xx cx16.r15 = ycenter - yy plot(cx16.r14, cx16.r15, color) cx16.r14 = xcenter - xx plot(cx16.r14, cx16.r15, color) cx16.r14 = xcenter + yy cx16.r15 = ycenter + xx plot(cx16.r14, cx16.r15, color) cx16.r14 = xcenter - yy plot(cx16.r14, cx16.r15, color) cx16.r14 = xcenter + yy cx16.r15 = ycenter - xx plot(cx16.r14, cx16.r15, color) cx16.r14 = xcenter - yy plot(cx16.r14, cx16.r15, color) yy++ if decisionOver2<=0 decisionOver2 += (yy as word)*2+1 else { xx-- decisionOver2 += (yy as word -xx)*2+1 } } } sub disc(uword @zp xcenter, uword @zp ycenter, ubyte @zp radius, ubyte color) { ; Midpoint algorithm, filled if radius==0 return ubyte @zp yy = 0 word @zp decisionOver2 = (1 as word)-radius while radius>=yy { horizontal_line(xcenter-radius, ycenter+yy, radius*$0002+1, color) horizontal_line(xcenter-radius, ycenter-yy, radius*$0002+1, color) horizontal_line(xcenter-yy, ycenter+radius, yy*$0002+1, color) horizontal_line(xcenter-yy, ycenter-radius, yy*$0002+1, color) yy++ if decisionOver2<=0 decisionOver2 += (yy as word)*2+1 else { radius-- decisionOver2 += (yy as word -radius)*2+1 } } } sub plot(uword @zp x, uword y, ubyte color) { ubyte[8] @shared bits = [128, 64, 32, 16, 8, 4, 2, 1] ubyte[4] @shared mask4c = [%00111111, %11001111, %11110011, %11111100] ubyte[4] @shared shift4c = [6,4,2,0] when active_mode { 1 -> { ; lores monochrome %asm {{ lda x eor y ora monochrome_dont_stipple_flag and #1 }} if_nz { %asm {{ lda x and #7 pha ; xbits }} x /= 8 x += y*(320/8) %asm {{ stz cx16.VERA_CTRL stz cx16.VERA_ADDR_H lda x+1 sta cx16.VERA_ADDR_M lda x sta cx16.VERA_ADDR_L ply ; xbits lda bits,y ldy color beq + tsb cx16.VERA_DATA0 bra ++ + trb cx16.VERA_DATA0 + }} } } ; TODO mode 2,3 4 -> { ; lores 256c void addr_mul_24_for_lores_256c(y, x) ; 24 bits result is in r0 and r1L (highest byte) %asm {{ stz cx16.VERA_CTRL lda cx16.r1 ora #%00010000 ; enable auto-increment so next_pixel() can be used after this sta cx16.VERA_ADDR_H lda cx16.r0+1 sta cx16.VERA_ADDR_M lda cx16.r0 sta cx16.VERA_ADDR_L lda color sta cx16.VERA_DATA0 }} } 5 -> { ; highres monochrome %asm {{ lda x eor y ora monochrome_dont_stipple_flag and #1 }} if_nz { %asm {{ lda x and #7 pha ; xbits }} x /= 8 x += y*(640/8) %asm {{ stz cx16.VERA_CTRL stz cx16.VERA_ADDR_H lda x+1 sta cx16.VERA_ADDR_M lda x sta cx16.VERA_ADDR_L ply ; xbits lda bits,y ldy color beq + tsb cx16.VERA_DATA0 bra ++ + trb cx16.VERA_DATA0 + }} } } 6 -> { ; highres 4c ; TODO also mostly usable for lores 4c? void addr_mul_24_for_highres_4c(y, x) ; 24 bits result is in r0 and r1L (highest byte) cx16.r2L = lsb(x) & 3 ; xbits color &= 3 color <<= shift4c[cx16.r2L] ; TODO with lookup table %asm {{ stz cx16.VERA_CTRL lda cx16.r1L sta cx16.VERA_ADDR_H lda cx16.r0H sta cx16.VERA_ADDR_M lda cx16.r0L sta cx16.VERA_ADDR_L ldy cx16.r2L ; xbits lda mask4c,y and cx16.VERA_DATA0 ora color sta cx16.VERA_DATA0 }} } } } sub pget(uword @zp x, uword y) -> ubyte { when active_mode { 1 -> { ; lores monochrome %asm {{ lda x and #7 pha ; xbits }} x /= 8 x += y*(320/8) %asm {{ stz cx16.VERA_CTRL stz cx16.VERA_ADDR_H lda x+1 sta cx16.VERA_ADDR_M lda x sta cx16.VERA_ADDR_L ply ; xbits lda plot.bits,y and cx16.VERA_DATA0 beq + lda #1 + }} } ; TODO mode 2 and 3 4 -> { ; lores 256c void addr_mul_24_for_lores_256c(y, x) ; 24 bits result is in r0 and r1L (highest byte) %asm {{ stz cx16.VERA_CTRL lda cx16.r1 sta cx16.VERA_ADDR_H lda cx16.r0+1 sta cx16.VERA_ADDR_M lda cx16.r0 sta cx16.VERA_ADDR_L lda cx16.VERA_DATA0 }} } 5 -> { ; hires monochrome %asm {{ lda x and #7 pha ; xbits }} x /= 8 x += y*(640/8) %asm {{ stz cx16.VERA_CTRL stz cx16.VERA_ADDR_H lda x+1 sta cx16.VERA_ADDR_M lda x sta cx16.VERA_ADDR_L ply ; xbits lda plot.bits,y and cx16.VERA_DATA0 beq + lda #1 + }} } 6 -> { ; hires 4c void addr_mul_24_for_highres_4c(y, x) ; 24 bits result is in r0 and r1L (highest byte) %asm {{ stz cx16.VERA_CTRL lda cx16.r1L sta cx16.VERA_ADDR_H lda cx16.r0H sta cx16.VERA_ADDR_M lda cx16.r0L sta cx16.VERA_ADDR_L lda cx16.VERA_DATA0 sta cx16.r0L }} cx16.r1L = lsb(x) & 3 cx16.r0L >>= gfx2.plot.shift4c[cx16.r1L] ; TODO with lookup table return cx16.r0L & 3 } else -> return 0 } } sub position(uword @zp x, uword y) { ubyte bank when active_mode { 1 -> { ; lores monochrome cx16.r0 = y*(320/8) + x/8 cx16.vaddr(0, cx16.r0, 0, 1) } ; TODO modes 2,3 4 -> { ; lores 256c void addr_mul_24_for_lores_256c(y, x) ; 24 bits result is in r0 and r1L (highest byte) bank = lsb(cx16.r1) cx16.vaddr(bank, cx16.r0, 0, 1) } 5 -> { ; highres monochrome cx16.r0 = y*(640/8) + x/8 cx16.vaddr(0, cx16.r0, 0, 1) } 6 -> { ; highres 4c void addr_mul_24_for_highres_4c(y, x) ; 24 bits result is in r0 and r1L (highest byte) bank = lsb(cx16.r1) cx16.vaddr(bank, cx16.r0, 0, 1) } } } sub position2(uword @zp x, uword y, bool also_port_1) { position(x, y) if also_port_1 { when active_mode { 1, 5 -> cx16.vaddr(0, cx16.r0, 1, 1) ; TODO modes 2, 3 4, 6 -> { ubyte bank = lsb(cx16.r1) cx16.vaddr(bank, cx16.r0, 1, 1) } } } } inline asmsub next_pixel(ubyte color @A) { ; -- sets the next pixel byte to the graphics chip. ; for 8 bpp screens this will plot 1 pixel. ; for 1 bpp screens it will plot 8 pixels at once (color = bit pattern). ; for 2 bpp screens it will plot 4 pixels at once (color = bit pattern). %asm {{ sta cx16.VERA_DATA0 }} } asmsub next_pixels(uword pixels @AY, uword amount @R0) clobbers(A, Y) { ; -- sets the next bunch of pixels from a prepared array of bytes. ; for 8 bpp screens this will plot 1 pixel per byte. ; for 1 bpp screens it will plot 8 pixels at once (colors are the bit patterns per byte). ; for 2 bpp screens it will plot 4 pixels at once (colors are the bit patterns per byte). %asm {{ phx sta P8ZP_SCRATCH_W1 sty P8ZP_SCRATCH_W1+1 ldx cx16.r0+1 beq + ldy #0 - lda (P8ZP_SCRATCH_W1),y sta cx16.VERA_DATA0 iny bne - inc P8ZP_SCRATCH_W1+1 ; next page of 256 pixels dex bne - + ldx cx16.r0 ; remaining pixels beq + ldy #0 - lda (P8ZP_SCRATCH_W1),y sta cx16.VERA_DATA0 iny dex bne - + plx }} } asmsub set_8_pixels_from_bits(ubyte bits @R0, ubyte oncolor @A, ubyte offcolor @Y) { ; this is only useful in 256 color mode where one pixel equals one byte value. %asm {{ phx ldx #8 - asl cx16.r0 bcc + sta cx16.VERA_DATA0 bra ++ + sty cx16.VERA_DATA0 + dex bne - plx rts }} } const ubyte charset_bank = $1 const uword charset_addr = $f000 ; in bank 1, so $1f000 sub text_charset(ubyte charset) { ; -- select the text charset to use with the text() routine ; the charset number is the same as for the cx16.screen_set_charset() ROM function. ; 1 = ISO charset, 2 = PETSCII uppercase+graphs, 3= PETSCII uppercase+lowercase. cx16.screen_set_charset(charset, 0) } sub text(uword @zp x, uword y, ubyte color, uword sctextptr) { ; -- Write some text at the given pixel position. The text string must be in screencode encoding (not petscii!). ; You must also have called text_charset() first to select and prepare the character set to use. ; NOTE: in monochrome (1bpp) screen modes, x position is currently constrained to multiples of 8 ! TODO allow per-pixel horizontal positioning ; TODO draw whole horizontal spans using vera auto increment if possible, instead of per-character columns uword chardataptr when active_mode { 1, 5 -> { ; monochrome mode, either resolution cx16.r2 = 40 if active_mode==5 cx16.r2 = 80 while @(sctextptr) { chardataptr = charset_addr + (@(sctextptr) as uword)*8 cx16.vaddr(charset_bank, chardataptr, 1, 1) position(x,y) %asm {{ lda cx16.VERA_ADDR_H and #%111 ; don't auto-increment, we have to do that manually because of the ora sta cx16.VERA_ADDR_H lda color sta P8ZP_SCRATCH_B1 ldy #8 - lda P8ZP_SCRATCH_B1 bne + ; white color, plot normally lda cx16.VERA_DATA1 eor #255 ; black color, keep only the other pixels and cx16.VERA_DATA0 bra ++ + lda cx16.VERA_DATA0 ora cx16.VERA_DATA1 + sta cx16.VERA_DATA0 lda cx16.VERA_ADDR_L clc adc cx16.r2 sta cx16.VERA_ADDR_L bcc + inc cx16.VERA_ADDR_M + inc x bne + inc x+1 + dey bne - }} sctextptr++ } } 4 -> { ; lores 256c while @(sctextptr) { chardataptr = charset_addr + (@(sctextptr) as uword)*8 cx16.vaddr(charset_bank, chardataptr, 1, 1) repeat 8 { position(x,y) y++ %asm {{ phx ldx color lda cx16.VERA_DATA1 sta P8ZP_SCRATCH_B1 ldy #8 - asl P8ZP_SCRATCH_B1 bcc + stx cx16.VERA_DATA0 ; write a pixel bra ++ + lda cx16.VERA_DATA0 ; don't write a pixel, but do advance to the next address + dey bne - plx }} } x+=8 y-=8 sctextptr++ } } 6 -> { ; hires 4c ; we're going to use a few cx16 registers to make sure every variable is in zeropage in the inner loop. cx16.r11L = color cx16.r8 = y while @(sctextptr) { chardataptr = charset_addr + (@(sctextptr) as uword)*8 repeat 8 { ; TODO rewrite this inner loop partly in assembly ; requires expanding the charbits to 2-bits per pixel (based on color) ; also it's way more efficient to draw whole horizontal spans instead of per-character cx16.r9L = cx16.vpeek(charset_bank, chardataptr) ; get the 8 horizontal character bits cx16.r7 = x repeat 8 { cx16.r9L <<= 1 if_cs plot(cx16.r7, cx16.r8, cx16.r11L) cx16.r7++ } chardataptr++ cx16.r8++ } x+=8 cx16.r8-=8 sctextptr++ } } } } asmsub cs_innerloop640() clobbers(Y) { %asm {{ ldy #80 - stz cx16.VERA_DATA0 stz cx16.VERA_DATA0 stz cx16.VERA_DATA0 stz cx16.VERA_DATA0 stz cx16.VERA_DATA0 stz cx16.VERA_DATA0 stz cx16.VERA_DATA0 stz cx16.VERA_DATA0 dey bne - rts }} } asmsub addr_mul_24_for_highres_4c(uword yy @R2, uword xx @R3) clobbers(A, Y) -> uword @R0, uword @R1 { ; yy * 160 + xx/4 (24 bits calculation) ; 24 bits result is in r0 and r1L (highest byte) %asm {{ ldy #5 - asl cx16.r2 rol cx16.r2+1 dey bne - lda cx16.r2 sta cx16.r0 lda cx16.r2+1 sta cx16.r0+1 asl cx16.r0 rol cx16.r0+1 asl cx16.r0 rol cx16.r0+1 ; xx >>= 2 (xx=R3) lsr cx16.r3+1 ror cx16.r3 lsr cx16.r3+1 ror cx16.r3 ; add r2 and xx (r3) to r0 (24-bits) stz cx16.r1 clc lda cx16.r0 adc cx16.r2 sta cx16.r0 lda cx16.r0+1 adc cx16.r2+1 sta cx16.r0+1 bcc + inc cx16.r1 + clc lda cx16.r0 adc cx16.r3 sta cx16.r0 lda cx16.r0+1 adc cx16.r3+1 sta cx16.r0+1 bcc + inc cx16.r1 + rts }} } asmsub addr_mul_24_for_lores_256c(uword yy @R0, uword xx @AY) clobbers(A) -> uword @R0, ubyte @R1 { ; yy * 320 + xx (24 bits calculation) %asm {{ sta P8ZP_SCRATCH_W1 sty P8ZP_SCRATCH_W1+1 lda cx16.r0 sta P8ZP_SCRATCH_B1 lda cx16.r0+1 sta cx16.r1 sta P8ZP_SCRATCH_REG lda cx16.r0 asl a rol P8ZP_SCRATCH_REG asl a rol P8ZP_SCRATCH_REG asl a rol P8ZP_SCRATCH_REG asl a rol P8ZP_SCRATCH_REG asl a rol P8ZP_SCRATCH_REG asl a rol P8ZP_SCRATCH_REG sta cx16.r0 lda P8ZP_SCRATCH_B1 clc adc P8ZP_SCRATCH_REG sta cx16.r0+1 bcc + inc cx16.r1 + ; now add the value to this 24-bits number lda cx16.r0 clc adc P8ZP_SCRATCH_W1 sta cx16.r0 lda cx16.r0+1 adc P8ZP_SCRATCH_W1+1 sta cx16.r0+1 bcc + inc cx16.r1 + lda cx16.r1 rts }} } }